This section provides background information related to the present disclosure which is not necessarily prior art. Oxygen sensors may be used in automotive vehicle applications to improve fuel economy, ensure smooth performance, and reduce exhaust emissions. Oxygen sensors are typically located in the exhaust system before and after the exhaust catalyst in order to determine catalyst efficiency. In this way, pre-catalyst and post-catalyst signals may be monitored and adjusted to meet emissions regulations. Most vehicles today include from two to four oxygen sensors, but additional sensors may be used as tail pipe gas emission regulations become more stringent to improve the quality of tail pipe gas emissions.
In operation, oxygen sensors may have a ceramic cylinder tip to measure the proportion of oxygen in the exhaust gas flowing out of the engine. Oxygen sensor measurements are most accurate when the sensor is heated to a specific temperature range, or a specific temperature, such as approximately 800° C. (1,472° F.). Accordingly, each sensor may include at least one heating element to allow the sensor to reach an ideal temperature more quickly, such as when the exhaust is cold, such as at initial engine start-up. The temperature of the ceramic portion of the sensor may vary with respect to the exhaust gas temperature in order to maintain accuracy of the sensor signal.
After measuring the proportion of oxygen in the exhaust gas, the sensor then generates a voltage signal representing the difference between the exhaust gas and the air external to the internal combustion engine (i.e. air-fuel ratio). Depending on the style of sensor, the sensor may instead create a change in resistance signal to convey the same information. The signal is transmitted through signal wires to a powertrain control module (PCM) where the signal is compared with the stoichiometric air-fuel ratio (e.g. 14.7:1 by mass for gasoline) to determine if the air-fuel ratio is rich (e.g. unburned fuel vapor) or lean (e.g. excess oxygen). The PCM can then vary the fuel injector output to affect the desired air-fuel ratio and to ultimately optimize engine performance.
The sensor is typically powered through the various attached wires. For example, signal wires and heater wires may be used to provide power to the sensor and the heating elements, respectively. As exhaust gas emissions regulations become more stringent and more sensors, as a result, are used, additional wiring may be necessary. Additional wiring may provide added complexity, increased assembly costs, and increased natural resource consumption (e.g. copper and plastics). Additionally, sensor failure may occur at the various sensor wires (e.g. power wires, heater wires) due to improper wiring, connector corrosion, or wire failure. When the oxygen sensor fails, the PCM can no longer sense the air-fuel ratio. Vehicle performance may be impacted and excess fuel, such as gasoline, may be consumed by the engine.